Description of Published Research

Avian Vocal Mimicry in Tawny Larks (Galerida deva)

The Sykes’s (Tawny) lark (Galerida deva) is a little-known endemic of the Indian subcontinent. The famous Indian ornithologist Salim Ali describes it as a remarkable vocal mimic, yet the extent and diversity of its mimicry has not been described in detail. Taylor Crisologo, a Cornell undergrad interested in avian vocal mimicry; Viral Joshi, a bird recordist from Gujarat, India and I published a paper where we describe the incredible variety of birds the Sykes’s larks mimic in Viral’s native Amareli in Gujarat. Using acoustic analysis, we also measured how accurate the larks were at mimicking species they regularly mimicked. Among the calls we analyzed, Sykes’s larks mimicked 34 species of birds. While they mimic some birds very accurately, the figure shows the spectogram of a common babbler and its mimicry by the lark below, other species mimicry by larks is easily distinguishable in structure with acoustic analysis. This study will hopefully lead to more studies on the function of mimicry in this species.

Significant range-overestimation for Western Ghats endemic birds

The total range size of a bird species is an important determinant of its probability of extinction according to the IUCN. In a recently published paper, we showed that species distribution models for 18 Western Ghats endemic birds predict that these species are found in a much smaller subset of their distributional range. This has significant implications for their IUCN threat categorizations. Check it out here!

Interspecific competition among Himalayan titmice?

Elevational species replacement is a widespread pattern among montane birds. Interspecific competition is considered an important driver of elevational distribution on tropical mountains but its importance in temperate systems has not been widely tested. We studied whether interspecific competition drives the distribution of two Himalayan birds the cinereous tit and the green-backed tit. We carried out behavioral experiments to study competition over space (playbacks) and competition over food (feeder trials). We show that although green-backed tits are behaviorally dominant over cinereous tits, habitat might be more important in driving the distribution of these two species. This study was recently accepted for publication in the Journal of Avian Biology.

Hypobaric hypoxia represents an important physiological stressor for montane organisms. We demonstrate that physiological strategies to cope with hypoxia vary among birds with the duration of time species spend in hypoxic conditions annually. Taking a novel comparative physiology approach we studied variation in haemoglobin concentration across nine elevational migrants, which live at high-elevations for only 4-6 months/year, and six year-round high-elevation resident birds across a 2200m Himalayan elevational gradient. We show that elevational migrants increase blood haemoglobin concentration by increasing haematocrit (red-cell volume) which is significantly different from high-elevation residents which increase mean cellular haemoglobin concentration to cope with hypoxia. Read it here

A Comprehensive Bird Checklist From Our Field-site (Chopta-Mandal)

Two technicians Soham Dixit and Viral Joshi who worked with me during my 2015 field season and I just published a paper on the elevational distribution of birds in my study site in the western Himalayas. Check out the paper here. I feel its extremely important to document and publish natural history as it can serve as a baseline for future studies and work toward filling the so-called “Wallacean short-fall”. Last year, Andre Dhondt (my PhD advisor) and I published the first description of a nest of yellow-browed tit (Sylviparus modestus) from India. It’s the western-most and elevationally highest nest described so far.

Fruiting Season Length Drives Global Distribution of Female Only Care in Frugivorous Passerines

Contingas, manikins and birds of paradise are some of the best examples of how elaborate, ornate and crazy male bird plumage can get. These birds also have some thing else in common. They are all frugivores and have female-only parental care where the male’s only role in reproduction is mating with the female. The female then goes on to build the nest and raise chicks all by herself. Due to several other reasons, all tropical birds have small clutch sizes and frugivores more so, often having a brood of one or two eggs. Frank La Sorte and I predicted that if the female has to do it all alone, then such a feat is only possible in areas where the fruiting seasons are really long so females can have abundant food resources for lengthy periods of time in which she can raise multiple small broods. We did a global analysis involving all frugivorous passerines and show that female-only care birds are concentrated in areas with the longest fruiting seasons in the equatorial tropics. Frugivores away from the equator are more likely to be species showing bi-parental care and probably with males that aren’t as flashy as birds of paradise.

Cavity nesting affects the life history evolution of Old World Flycatchers.

Nick Mason and I tested some long standing predictions of the effect of cavity nesting on the life history of birds, in a comparative phylogenetic framework. We chose the Muscicapidae or Old World Flycatchers as our candidate group because of a good dispersion of cavity-nesting and open-nesting traits across species. We discovered that cavity nesting has evolved multiple times independently in this group. We show that interspecific competition has had a strong impact on which species are cavity nesting. We also show that migratory behavior is much more common in cavity nesting lineages than open nesting lineages and hence cavity nesting has been crucial for the evolution of migratory behavior in Old World Flycatchers. Read the paper here and coverage about it here. The figure shows the most comprehensive phylogeny of muscicapidae till date.

Morphometry of Himalayan birds

Over the past 3 years, I have been collecting detailed morphological and natural history data on west Himlayan birds through mist netting across a 2500m elevational gradient. I have data on beak, wing, tarsus, mass, breeding status and other ecological variables for more than 1500 individual birds of more than 100 species. Write to me if you would like to request any data. The data is a result of a lot of hard-work and I would expect a formal collaboration before I can share data.